Millimeter wave systems that perform beam forming and steering typically include numerous antenna elements, integrated circuits and interconnects. Such systems are the foundation of a viable mechanism to provide high data rate short-range wireless connectivity for consumer applications. In order to achieve performance and cost points, a prevalent challenge is to develop an integration platform package that is compatible with volume manufacturing and assembly processes.
Such an integrated package is expected to accommodate a variety of functions as the level of integration increases. These functions include providing low-loss resonance-free mm-wave signal paths, embedding of multi-layer antenna elements and their feed network, integrating local oscillator (LO), intermediate frequency (IF) distribution and passive circuits and incorporating control and bias layers among others.
In a typical scenario where a millimeter-wave antenna is to be integrated with an integrated circuit (IC), both the antenna and the IC reside on the top layer of a substrate to ensure acceptable performance. This approach encounters problems when there are many antenna elements that need to be individually driven by distinct RF ports located on one or more ICs. First, routing congestion will limit the number of elements.
Moreover, the package will be large as ICs and antennas have to be located on the same surface with enough clearance. As the size of the package increases, the cost will increase, and in some cases, the substrate may even become too large to be manufactured. Finally, heat removal from the ICs would be difficult.